Door Viewer, 180 Degrees, 1/2" Bore Hole, Adjusts from 1-3/8" to 2-1/8", Polished Brass by Stone Harbor Hardware

It was easy to install and provided good viewing

Only has glass on one side. On the inside of the door it's just an open tube collecting dust.

Good: it works. It covered the 1/2 hole. I can see out.Bad:1. It is ever so slightly bigger than 1/2 inch. I had a peephole before, replaced it with a peephole camera but the camera stopped working so I got this to replace the camera and it didn't fit initially. After having other peepholes I knew that it was this product that was not quite right. I measured it and it was really close but biggerIt is a metal door so I had to scrape out a few shavings more. I got it to work.2. Security is not good. The peephole is small enough on the interior side which makes it possible to yank through with strong force, especially if the hole is even a bit loose.2b. It does not have a security cover.Both of these are real issues but not every security threat would be able to exploit the issue.